The present invention relates to an electrical connector for a circuit board.
An electrical connector for a circuit board is connected by soldering connecting sections of terminals of the connector to a corresponding circuit portion of a circuit board upon attaching to the circuit board. A connector of this type has been known as one disclosed in Patent Reference.    Patent Reference: Japanese Patent Publication No. 2008-226681
The connector of Patent Reference has a housing having a circumferential wall, which extends orthogonally to a circuit board surface to receive a mating connector, and the terminals are integrally molded onto the facing side walls of the circumferential wall. Each terminal has a contact section provided along an inner surface of the side wall and a connecting section that is bent at its end and extends outside the housing. Each terminal contacts with a terminal of a mating connector at the contact section, and is connected by soldering at the connecting section to a corresponding circuit portion of a circuit board.
In the connector of Patent Reference, each terminal has in its longitudinal direction, a first and a second low solder wetting areas on a circumferential surface, which is a portion between a connecting section and a housing side wall, and a lower face of a portion, where the terminal is integrally molded and thereby held by the side wall of the housing, respectively. According to Patent Reference, if the connecting section of each terminal is connected to a circuit board by soldering, the solder wicking is restricted at the first and the second low solder wetting areas.
In the connector of Patent Reference, the terminals are integrally molded to the housing and thereby held therein, so that the side walls of the housing, which hold the circumferential surface of each terminal tightly contacts with a circumferential surface of the terminal. Therefore, except of unexpected situation such as partial peeling to impair the tight contact, there is no concern of solder wicking. Accordingly, it is also possible to consider that the first and the second low solder wetting areas are for the unexpected situation like the aforementioned partial peeling.
Regardless whether the terminals are integrally molded to the housing, in case of a connector to be attached to a wall of housing after molding, since small space is formed between a terminal and a wall of the housing, it is necessary to make sure to prevent solder wicking. Generally speaking, for prevention against solder wicking, as described in Patent Reference, a low solder wetting area such as nickel plating is formed on a circumferential surface of a portion between a connecting section and a contact section of each terminal.
Since terminals are required to have good conductivity, each terminal includes a nickel plating layer as a base layer on a base material surface, and a gold plating layer, which is a high solder wetting material and has good conductivity, as an upper layer thereon. To form a low solder wetting area, the gold plating layer is removed or melted at the portion by laser or the like, and as a result, the nickel layer is exposed and thereby a low solder wetting area is formed.
While the connecting section has to be well soldered to a circuit portion of a circuit board, the contact section has to secure the gold plating layer with good conductivity as wide as possible. More specifically, while the connecting section and the contact section are required to be formed wide as high solder wetting areas, the low solder wetting area provided between the connecting section and the contact section is required to be formed in an area that is as wide as possible to make sure prevention against solder wicking.
Accordingly, the high solder wetting areas at the connecting section and the contact section and the low solder wetting area provided therebetween require to satisfy contradictory conditions. In this circumstance, it is difficult to meet the contradictory conditions also in view of the low profile demand.
In view of the above, there is provided an invention, an object of which is to provide an electrical connector for a circuit board, which can securely prevent solder wicking in a low solder wetting area between the connecting sections and contact sections of terminals while maintaining good soldering property at the connecting sections and good electrical conductivity at the contact sections.
Further objects and advantages of the invention will be apparent from the following description of the invention.